It is often desirable to provide a barrier that blocks or filters sunlight or otherwise screens, wind, rain, and/or other environmental phenomena from entering or exiting a selected space, such as a room or building. There are, of course, many different types of barriers that have been used over the centuries to accomplish this goal, ranging from solid opaque walls and roofs made from, for example, stone, wood, brick, stucco, concrete, or the like, to shutters or louvers, to transparent or translucent glass, to wax paper, and so on.
One exemplary barrier is a building façade. Building facades mediate between interior and exterior thermal conditions, providing passage of air and sunlight when requested while blocking their passage when it is undesirable. Over the past few decades, buildings with glazed building facades, i.e., facades substantially composed of glass window and wall systems, have become popular as they provide transparency. While these glazed building facades are beneficial in many ways, they also have environmental disadvantages in comparison with traditional opaque building facades, such as increased heat gain in summer, light pollution (also known as spill light), glare, and increased heat loss in winter.
The present inventor has been inspired from a focus on designing energy efficient building façades and an attempt to achieve optimum daylight levels and energy conservation by providing buildings with optimum openings. This is coupled with a basic understanding that openings through the building façade are an important component in building design and play a key role in saving energy and utilizing daylight. Further, effective use of daylight inside the building can be an important way to achieve energy cost savings. Therefore, strategies for optimizing the energy efficient use of daylight in architectural systems should be considered when designing openings in the building facade in order to meet daylight requirements and increase energy conservation.
Although currently known curtain wall glazing systems can balance the size and number of openings through the building facade to achieve energy conservation and optimum daylight levels, these systems allow tremendous amounts of energy to enter and exit through windows. Therefore, one goal of the present inventor is to provide a new barrier for openings that can be controllably adjusted between allowing a minimum transfer of light to allowing a maximum transfer of light with a minimum of movement of the barrier, thus saving operating energy costs and providing a more energy-efficient building facade. Another goal is to provide such adjustable barriers in openings with a limited amount of space or where lighting can be controlled during the course of the day. Of course, these and/or other goals and ends may be achieved with the systems disclosed herein in different forms and applications.
In searching for new solutions to these problems, the present inventor looked, surprisingly, to an ancient device used to control the transmission of light, such as by blocking or obscuring light: the curtain. In general terms, a curtain is normally considered to be a panel of flexible sheet material, such as cloth, plastic, or netting, that hangs downwardly from an upper support. In some instances, the curtain hangs freely under the force of gravity from the upper support, for example by having the upper support connected to a top edge of the panel with no other retention devices attached to the flexible sheet material. In other instances, the curtain is maintained in a taught condition by one or more additional retention mechanisms attached to other areas, such as a bottom edge and/or side edges of the panel.
A characteristic feature common to curtains and curtain systems until now has been that, in order to open or close the curtain to change the amount of light or air allowed therethrough, the panel must be moved in a manner that substantially changes the overall outline shape of the panel or change the entire position of the panel. For example, one side edge of the panel may be drawn toward an opposite side edge, or the bottom edge may be drawn up toward the top edge. Of course, the entire panel may be moved, such as to the side or by complete removal.
Curtains are used to block or obscure light in many different environments and applications. Some common environments in which curtain systems are used include windows or doorways, as room dividers, as exterior building walls, to divide one outdoor space from an adjacent outdoor space, in underwater environments, in space, in machines, in vehicles, and so on. However, until now, developments in the design of curtains has been generally limited to aesthetic choices and systems for hanging and moving the entire panel between open and closed positions. The fundamental design of the curtain panel has remained relatively unchanged from a basic panel made of cloth or other flexible material. Although these known barriers are often effective, the inventor of the curtain systems disclosed herein has attempted to provide a curtain system with which one can change the light and/or air transmission properties of the barrier in a fundamentally different way.